Speed cameras that shame drivers into slowing down rather than fining them may be introduced on English motorways.
The cameras flash up the speed limit and drivers' number plates
The cameras record the number plates of speeding drivers and flash them up on a screen but do not issue penalties.
They were used during June along a stretch of the M42 in the West Midlands and proved a success with nearly half of speeding drivers slowing down.
Now the Highways Agency has said the signs could be extended to other English motorways and major routes.
A spokeswoman for the agency said it was the next step on from signs seen in many villages which flash up the speed limit and the words "Slow Down" when drivers are recorded speeding.
"Once the speeding vehicle activates the sign that vehicle registration number is shown at the same time.
"What we are doing is personalising it - it is moral blackmail in a way."
She said the fact that the cameras did not issue fines showed they were not only "revenue raisers" as portrayed by newspapers.
The trial was carried out by consultants Atkins between junctions 9 and 10 of the M42 in Warwickshire when the limit was reduced to 50mph for roadworks.
The system would be used on stretches of road where works were being carried out. In 2004, there were more than 700 accidents at roadworks in the UK- 12 of which were fatal.
Atkins director Richard Deacon said: "All road workers are at risk from speeding drivers and we are committed to reducing this danger.
"This innovative system, which brings together two well-established technologies, provides a targeted approach that has proved most effective in encouraging drivers to adhere to the speed limit in roadworks."
The Highways Agency said number plate information was not stored once it has flashed on the screen.
Paul Smith, from anti-speed camera pressure group Safe Speed said it was a move in the right direction.
However, he added: "We will not get road safety back on track until all the speed cameras are scrapped."